1. Field of the Invention
The present invention is directed to a process and apparatus for comminuting phytosterol particles to a particle size suitable for use as a food additive. More particularly, the present invention is directed to a process and apparatus for comminuting phytosterol in significantly larger amounts and at greater mass velocity than heretofore produced.
2. Background of the Prior Art
Phytosterols, also known as plant sterols, are a naturally occurring class of compounds found in the cells and membranes of plants. These plant lipid-like compounds are present in low levels in grains, fruits and vegetables. There are approximately 250 different sterols and related compounds in plant and marine materials of which the most common abundant are β-sitosterol, stigmasterol and campesterol.
Phytosterols have a similar molecular structure to dietary and endogenously secreted cholesterol. The aforementioned three most common phytosterols differ from cholesterol only in the identity of one side chain or the presence of an extra bond. This molecular similarity between cholesterol and phytosterol molecules result in competition in the human body for absorption in the small intestine. Although phytosterols are absorbed in the small intestine, they are not absorbed into the blood stream. That is, most of the phytosterols ingested by human beings remains in the gastrointestinal tract. Indeed, phytosterol absorption into the body is limited to approximately 2% to approximately 15%, depending on the identity of the phytosterol.
The absorption of phytosterols in the intestine blocks the absorption of dietary cholesterol, which competes with phytosterols for absorption. Moreover, the reabsorption of cholesterol from bile acids in the digestive process in inhibited by phytosterols. As such, the intake of phytosterols inhibits the entrance of cholesterol into the blood stream.
The above description is a simplified explanation of the fact that phytosterols result in lowering of cholesterol levels in the blood stream. Insofar as cholesterol has been identified as a principal cause of heart disease, increase of phytosterols content in the human diet can significantly reduce blood cholesterol levels.
The addition of phytosterols to other foods is an excellent means for increasing phytosterol consumption in the diet. However, the commercially available phytosterol obtained from exploitation of plant products, such as soybean oil extraction, have a particle a size which makes addition of phytosterol, even in small concentration, detectable. That is, the relatively large size of phytosterol particles makes its introduction into liquid or solid foods detectable due to taste, odor and/or texture.
Unfortunately, phytosterol particles are not easily comminuted. This is so because the melting point of a typical phytosterol is in the range of between about 135° F. and 145° F. Thus, phytosterol particles melt, due to the heat of comminution, when phytosterol particles are conventionally ground. Therefore, there is a strong need in the art for a process and an apparatus for comminuting phytosterol particles, without degradation, to a suitably small particle size for non-detectable introduction into foods, in commercially significant volumes, to satisfy the predicted high volume requirements of this product.
The above need in the art for improved comminution of phytosterols is also indicated for other comestibles that are combinable with other foods for easy edibility. Such products as neutraceuticals, for example, Vitamins A, B1, C, D and E, folate and necessary dietary minerals, e.g. potassium, calcium and zinc, sugar substitutes, dietary supplements, food additives, food fortifiers and the like could find wider utility if they could be milled to smaller size for incorporation into other liquid and solid foods. Thus, the need in the art for an apparatus and process for comminuting phytosterol particles is not limited to that utility. Such an apparatus and process is also desired in the comminution of a large class of comestible food products, particularly those necessary for healthy diets.